Java 在spring集成JPA模型中插入期间获取异常

我正在使用Spring与hibernate集成，并在实体对象中使用JPA注释。我创建这个项目是为了使用这个组合测试CRUD操作。我能够从db加载数据，但面临插入问题

我有两张桌子

员工：ID、姓名、年龄、部门

部门：部门ID，部门名称

Employee.java

    @Entity
    @Table(name="EMPLOYEE")
    public class Employee implements Serializable {

        @Id
        @GeneratedValue(strategy=GenerationType.AUTO)
        @Column(name="ID")
        private int id;

        @Column(name="NAME")
        private String name;

        @Column(name="AGE")
        private int age;

        @ManyToOne
        @JoinColumn(name="DEPT", referencedColumnName="DEPT_NAME", updatable=false, insertable=false)
        private Dept department;

//Other getters and setters

爪哇省

@Entity
@Table(name="DEPT")
public class Dept implements Serializable {

    @Id
    @Column(name="DEPT_ID")
    private int deptId;

    @Column(name="DEPT_NAME")
    private String deptName;

    @OneToMany(cascade=CascadeType.ALL, mappedBy="department")
    private List<Employee> employee;

问题2: 另一个问题是，我正在使用entity类中自动生成的Employee ID，但如果我没有在表单中输入ID并单击submit，我将得到以下异常

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.springframework.validation.BindException: org.springframework.validation.BeanPropertyBindingResult: 2 errors
Field error in object 'employee' on field 'department': rejected value [VZW]; codes [typeMismatch.employee.department,typeMismatch.department,typeMismatch.com.spring.persistence.Dept,typeMismatch]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [employee.department,department]; arguments []; default message [department]]; default message [Failed to convert property value of type 'java.lang.String' to required type 'com.spring.persistence.Dept' for property 'department'; nested exception is java.lang.IllegalStateException: Cannot convert value of type [java.lang.String] to required type [com.spring.persistence.Dept] for property 'department': no matching editors or conversion strategy found]
Field error in object 'employee' on field 'id': rejected value []; codes [typeMismatch.employee.id,typeMismatch.id,typeMismatch.int,typeMismatch]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [employee.id,id]; arguments []; default message [id]]; default message [Failed to convert property value of type 'java.lang.String' to required type 'int' for property 'id'; nested exception is java.lang.IllegalArgumentException]
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:659)
    org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:563)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:722)

我甚至在谷歌上搜索答案，但找不到正确的答案。有人能帮我吗？ 谢谢

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附言：我没有在这里保存spring配置和web.xml文件。正如我已经提到的，检索操作正在工作，所以我相信配置应该是好的。

我确信问题不在JPA中，它与spring在控制器内的有效对象中转换表单参数的方式有关。 基本上，同一个问题有两个问题：

来自表单的值总是字符串的，所以在控制器中公开的bean应该将其所有属性都作为字符串，以便能够将表单的参数传递到bean属性中。我认为这个过程叫做绑定

这就是为什么我说： 无法将类型为“java.lang.String”的属性值转换为属性“department”所需的类型“com.spring.persistence.Dept”，始终发送字符串。但并非所有属性都是字符串，其中一个属性是Dept，因此无法进行转换

为了解决这个问题，您可以使用只包含字符串的POJO，这是最简单的解决方案，表单中的所有参数都应该在bean中命名为属性。为什么不尝试在控制器中使用bean表单之类的东西而不是实体bean

---

或者我认为一个更完整的解决方案是使用@modeldattribute和@InitBinder实现一些东西，对此不是很确定，所以请注意这个注释XD。

问题1:中强烈建议您使用Spring JSTL中的标记。它将解决此错误，并可能解决将来的错误

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问题2:不要在POJO中使用原语。而且我认为它与问题1有关

我想在这里使用单独的VO类，而不是这个实体类。但是在检索过程中，我看到实体正确地填充了相应类型的值。问题只会在插入时出现。让我尝试为deptName添加一个字符串类型的字段，看看会发生什么。在代码中有**@JoinColumn（name=“DEPT”，referencedColumnName=“DEPT\u name”，updateable=false，insertable=false）**尝试删除insertable=false。还要记住Dept的键是Dept_ID而不是字符串，使用joincolumn注释只会覆盖列的名称。请尝试启用CascadeType。PERSISTOk谢谢，让我试试。给我点时间。嘿，伙计，我也有同样的问题。你找到问题了吗。webinit是答案吗？

    @Controller
    public class EmployeeController {

        @Autowired
        private EmployeeDAO empDao;

        @Autowired
        private DeptDAO deptDao;

    @RequestMapping(value="/loadInsertForm", method=RequestMethod.GET)
        public String loadInsertForm(Model model){
            List<Dept> depList = deptDao.getDept();
            model.addAttribute("deptObjList", depList);
            return "empInsertForm";
        }

        @RequestMapping(value="/insertEmpValues", method=RequestMethod.POST)
        public String insertEmployee(Employee employee){
            empDao.saveEmployee(employee);
            return "loadEmpList";
        }

@RequestMapping(value="/loadEmpList", method=RequestMethod.POST)
    public String displayEmpDetails(Model model){
        List<Employee> emp = empDao.getEmployee();
        model.addAttribute("empList", emp);
        return "empList";
    }
    }

<form:form method="POST" action="insertEmpValues.spr" commandName="employee">
        <table width="30%">
            <tr>
                <td align="right">Employee ID : </td>
                <td><input type="text" name="id" /></td>
            </tr>
            <tr>
                <td align="right">Employee Name : </td>
                <td><input type="text" name="name" /></td>
            </tr>
            <tr>
                <td align="right">Age : </td>
                <td><input type="text" name="age" /></td>
            </tr>
            <tr>
                <td align="right">Department : </td>
                <td>
                    <select name="department">
                        <c:forEach items="${deptObjList}" var="dept">
                            <option id="${dept.deptName}">${dept.deptName}</option>
                        </c:forEach>
                    </select>
                </td>
            </tr>
            <tr>
                <td align="center" colspan="2">
                    <input type="submit" value="Submit" />
                </td>
            </tr>
        </table>
    </form:form>

exception 
org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.springframework.validation.BindException: org.springframework.validation.BeanPropertyBindingResult: 1 errors
Field error in object 'employee' on field 'department': rejected value [POS]; codes [typeMismatch.employee.department,typeMismatch.department,typeMismatch.com.spring.persistence.Dept,typeMismatch]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [employee.department,department]; arguments []; default message [department]]; default message [Failed to convert property value of type 'java.lang.String' to required type 'com.spring.persistence.Dept' for property 'department'; nested exception is java.lang.IllegalStateException: Cannot convert value of type [java.lang.String] to required type [com.spring.persistence.Dept] for property 'department': no matching editors or conversion strategy found]
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:659)
    org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:563)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:722)

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.springframework.validation.BindException: org.springframework.validation.BeanPropertyBindingResult: 2 errors
Field error in object 'employee' on field 'department': rejected value [VZW]; codes [typeMismatch.employee.department,typeMismatch.department,typeMismatch.com.spring.persistence.Dept,typeMismatch]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [employee.department,department]; arguments []; default message [department]]; default message [Failed to convert property value of type 'java.lang.String' to required type 'com.spring.persistence.Dept' for property 'department'; nested exception is java.lang.IllegalStateException: Cannot convert value of type [java.lang.String] to required type [com.spring.persistence.Dept] for property 'department': no matching editors or conversion strategy found]
Field error in object 'employee' on field 'id': rejected value []; codes [typeMismatch.employee.id,typeMismatch.id,typeMismatch.int,typeMismatch]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [employee.id,id]; arguments []; default message [id]]; default message [Failed to convert property value of type 'java.lang.String' to required type 'int' for property 'id'; nested exception is java.lang.IllegalArgumentException]
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:659)
    org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:563)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:722)